Hi all,
"Robert M. Hyatt" wrote:
[snip sig]
> On Mon, 25 Jan 1999, Neil Conway wrote:
>
> > Cris Wade wrote:
> > > I also think that you should follow Tim's advice and just get a celeron A.
> > > I got a celeron A 300 for just $85 US, and it nicely Overclocks to 450.
> >
> > This puzzles me: the reason advanced for the easy overclockability of
> > the original Celeron was that it came with NO L2 cache and that the
> > cache in the PII was the most speed-sensitive component.
> >
> > Now we have Celerons with 128kB of FULL_SPEED L2 cache and people can
> > still overclock by factors like 1.5? I'd have thought the full-speed L2
> > cache was closer to the limits than the half-speed stuff - weird...
> >
> > Anyone comment on this?
>
> its a manufacturing issue. They don't do a special 333 (or 366) mhz
> L2 for the celeron, they use the stock PII cache with 128kb rather than
> 512kb.
I'm probably dazed and confused in the normal Monday style, but I kind
of
thought alot of the issue was that the 128kB cache of the Celeron is
_on die_ - and so the speed limit would be a mixture of process
technology
and gate type/layout. It gets sort of hairy shoving 400MHz signals
across a
wide bus on a PCB, especially when you probably have a shed-load of
signals
switching at the same time on a (relatively) long wire-length (MCM jobs
like
the PPro are generally going to be better but, as Intel
found out, are a whole hunk more expensive if you can only run a full
test
on the assembled module). I'm not sure if the cache layout has been
taken
from the external L2 modules of the standard PII, or even if the process
size
is the same (probably is - i'll have a look around on Intels site) but
if
you're running in silicon with nice little interconnects, you're gonna
have
a fair bit of headroom speed-wise over an external cache :)
> Saves money by using economy of scale in production. IE it is
> cheaper to make 400mhz 128kb L2 modules than it is to make some 400mhz
> parts for the 400mhz xeons, and then make some different parts for the
> Celeron. So you _really_ get a good deal, but it is _very_ likely that
> Intel is going to stop the overclocking soon. CPUs are now clock locked
> already, but you can ramp up the bus speed to overclock, _if_ your memory
> and other things will run at the faster speed. But they are taking steps
> to lock the bus clock also, to stop this...
>
Yeah, looking at their recent comments this is going to happen sooner
rather
than later - some people just have _no_ sense of fun....
> >
> > Neil
> >
> > PS: No flames please. I'm interested for technical reasons only, and I
> > have no interest in actually overclocking any chips myself.
> > -
[snip]
--
--------------------------------------------------------------
Tim Parker Zuken-Redac,
Leading Software Engineer 1500 Aztec West,
Tel.no : (44) 1454 207800 ext 8710 Almondsbury,
Fax.no : (44) 1454 207803 Bristol,
E-Mail : [EMAIL PROTECTED] BS32 4RF. U.K.
"Any opinions are mine, and mine alone. They do not reflect
reality let alone this company"
--------------------------------------------------------------
-
Linux SMP list: FIRST see FAQ at http://www.irisa.fr/prive/mentre/smp-faq/
To Unsubscribe: send "unsubscribe linux-smp" to [EMAIL PROTECTED]
